An expression is a short set of instructions that tells an interactive presentation to do something. For example:

Box1.SetOpacity(50)

This expression tells an interactive presentation to set the opacity of the picture box named "Box1" to 50% opaque.

Each expression is made up of several parts. The following five components can go into an expression:

• Parameters
• Variables
• Operators
• Functions
• Objects

In this example, "Box1" is an object, "SetOpacity" is a function, and "50" is a parameter. By combining these parts in a specific order, we create an expression that tells an interactive presentation to place the text into the box.

• Parameters
  
• Variables
  
• Operators
  
• Functions
  
• Functions that require parameters
  
• Functions that return values
  
• Objects